This feature was added yesterday, comparing two sensors.
I think you can do this using a delayed rule combined with another one. First rule catches the change, second rule looks again later. Something like that might work…
When Rule Machine was first published, @slagle suggested this, and @Mike_Maxwell provided the parent app. Smart Lighting is done this way, as are both Rule Machine and Trigger Happy. It is documented here: http://docs.smartthings.com/en/latest/smartapp-developers-guide/parent-child-smartapps.html